Control of Acidosis and Increased Efficiency in Feedlot Nellore Cattle Fed with Moderate and High Energy Diets with the Addition of a Symbiotic Based on Beneficial Bacteria and Nutrients

• Grant number: 24/18643-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: June 01, 2025
• End date: July 31, 2027
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Kalista Eloisa Loregian
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

This study aims to evaluate different dosages of a probiotic based on beneficial bacteria and nutrients in diets containing moderate and high energy levels. Four Nellore steers fitted with a ruminal cannula, with an initial body weight of 300 kg will be used. The experimental design will follow a duplicated 4 × 4 Latin square, using moderate energy diets [35% starch, 1.19 Mcal/kg of net energy gain (NEG) per kg] and high energy diets [45% starch, 1.36 Mcal/kg of NEG per kg]. The diets will be composed of corn silage, ground corn, soybean hulls, cottonseed meal, urea, and mineral supplement. The treatments will consist of different levels of symbiotic inclusion at 0, 5, 10, and 15 grams per animal per day. Each experimental period will last 28 days (14 days for adaptation and 14 days for collection), with a 7-day washout between each period. The animals will be initially submitted to four periods on the moderate energy diet, followed by four periods on the high energy diet, totaling 273 days of experiment. Measurements will include dry matter intake, feeding behavior, ruminal degradability of nutrients, pH and redox potential of the rumen, ruminal fermentation pattern (short-chain fatty acids, ammonia, and lactate), ruminal disappearance rate, total gastrointestinal nutrient digestibility, and assessment of the ruminal microbiota (bacterial and protozoal communities). Data from this study will be analyzed using PROC MIXED of SAS (2003) through regression analysis of linear, quadratic, and cubic effects, considering a significance level of 5%. Data regarding the ruminal bacterial communities will be analyzed using Mothur and subsequently R.